import java.util.Stack;

/**
 * @Author @fiber-cloud
 * @Date 2025/8/3 15:46
 * 用栈实现队列
 */
public class MyQueue2 {
    private Stack<Integer> s1 ;
    private Stack<Integer> s2;



    public MyQueue2() {
        s1 = new Stack<>();
        s2 = new Stack<>();
    }

    //入栈
    public void push(int x) {
        s1.push(x);
    }

    public int pop() {
        if (empty()){
            return -1;
        }
        if (s2.empty()){
            while (!s1.empty()){
                s2.push(s1.pop());
            }
        }
        return s2.pop();
    }

    public int peek() {
        if (empty()){
            return -1;
        }
        if (s2.empty()){
            while (!s1.empty()){
                s2.push(s1.pop());
            }
        }
        return s2.peek();
    }

    public boolean empty() {
        return s1.empty() && s2.empty();
    }
}
